Processes

Question 1

What is the CPU-I/O Burst Cycle

Answer 1

Process execution consists of a cycle of CPU execution (CPU executing the program code) and I/O wait (waiting for the result of I/O)

Question 2

What is a charasteric of a CPU Bound Program

Answer 2

Program that has long CPU burst and short I/O wait

Question 3

What is the charateristics of a I/O Bound Program

Answer 3

Program that has long I/O wait and short CPU burst

Question 4

What is the ready queue

Answer 4

Set of all processes residing in main memory that are ready and waiting to execute

Question 5

What is the I/O queue

Answer 5

Set of all processes waiting for an I/O device. Each device has its own I/O device queue

Question 6

What does ht eProcess/CPU Scheduler do?

Answer 6

Select which process in ready queue need to be executed next by the CPU

Question 7

What are the scheduling criteria?

Answer 7

Maximize CPU Utilization, Maximize Throughput, Minimize Turnaround Time, Minimize Waiting Time and Minimize Response time

Question 8

What is CPU Utilization

Answer 8

Try to keep the CPU as busy as possible; i.e. executing as many processes as possible

Question 9

What is throughput

Answer 9

The number of processes that are completed per time unit; i.e. complete execution of as many processes as possible

Question 10

What is turnaround time?

Answer 10

The amount of time used to complete a process. Turnaround time = Execution time + Waiting Time

Question 11

Waht is waiting time?

Answer 11

The amount of time a process is waiting in the ready queue

Question 12

What is response time?

Answer 12

The amount of time used to output/display the first result

Question 13

What is Multilevel queue Scheduling

Answer 13

Partitioning a ready queue into multiple queues. Each queue has its own priority. Foreground processes have higher priority over the background processes

Question 14

What is IPC?

Answer 14

Inter-Process Communication. It is a communication among all processes

Question 15

What the the advantages of IPC

Answer 15

Information sharing, Computation Speed-up, Modularity and Convenience

Question 16

What are the two models of IPC?

Answer 16

Message passing and Shared Model

Question 17

What is message passing?

Answer 17

Process A sends/receives messages to/from process B through kernel (system calls). This model is only used for exchanging small data because it is slower, but it is more reliable than the shared model

Question 18

What is the shared memory model?

Answer 18

Both Process A and B write/read data on a shared memory. It is faster and more convenient than the message passing. It is used for exchanging larger amount of data

Question 19

In shared memory model what is the consumer?

Answer 19

Process that consumes information from the producer

Question 20

In shared memory model what is the producer?

Answer 20

Process that produces information that is consumed by a consumer process

Question 21

What is the Queue buffer?

Answer 21

Memory uses to temporarily sharing information between processes. It is based on queue concept (first in-first out). There are 2 types of queue buffer: Unbounded buffer and Bounded buffer

Question 22

What is an unbounded buffer?

Answer 22

There is no limit on the size of the buffer. Producer can keep producing data and place it on the buffer even when there’s no consumer. This is rarely used! Message passing model is used to inform the consumer when the queue is empty

Question 23

What is a bounded buffer?

Answer 23

The buffer has a fixed size. When the buffer is full, the producer cannot place a new data to the buffer. The producer must wait until the queue is not full anymore. Message passing model is used to inform the producer when the queue is full, and to inform the consumer when the queue is empty

Question 24

What is buffer overflow?

Answer 24

When a producer tries to place a new data to the bounded buffer which is already full

Question 25

What are the scheduling algorithms?

Answer 25

First-Come, First-Served Scheduling
Shortest-Job-First Scheduling
Priority Scheduling
Higher priority process always runs first
Round-robin Scheduling
All take turn based on time
Equal portions of time slices in circular order
Multilevel Queue Scheduling
Multilevel Feedback-Queue Scheduling